The size of the pupil has a large effect on visual function, and pupil size depends mainly on the adapting luminance, modulated by other factors. Over the last century, a number of formulas have been proposed to describe this dependence. Here we review seven published formulas and develop a new unified formula that incorporates the effects of luminance, size of the adapting field, age of the ob...

Humans often perform visual tasks together, and when doing so, they tend to devise division of labor strategies share the load. Implementing such strategies, however, is effortful as co-actors need coordinate their actions. We tested if pupil size – a physiological correlate mental effort can detect coordination in multiple object tracking task (MOT). Participants performed MOT jointly with com...

Rapid variations in cortical state during wakefulness have a strong influence on neural and behavioural responses and are tightly coupled to changes in pupil size across species. However, the physiological processes linking cortical state and pupil variations are largely unknown. Here we demonstrate that these rapid variations, during both quiet waking and locomotion, are highly correlated with...

BACKGROUND/AIMS Well dilated pupils make eye surgery easier. A classic twin study was established to examine the relative importance of genes and environment in the variance of pupil size after mydriasis, and to examine the effects of other factors such as age, iris colour, and refractive error. METHODS 506 twin pairs, 226 monozygotic (MZ) and 280 dizygotic (DZ), aged 49-79 (mean age 62.2 yea...

PURPOSE Pupillary examination is an important objective method to diagnose lesions of the anterior visual pathways. However, errors and faults may easily alter the interpretation and value of the test as it is highly dependent on the examiner's skills. Therefore, we tried to develop a pupillography which is independent of the examiner. METHODS Hardware composed of a binocularly measuring inst...

Reply: We would like to thank Cheng et al. for their comments. The Zywave unit used by them (commercial software 5.09) is different from the one used in our study (software 4.45SP2). Using the pupillometry function, software 5.09 has no fixation target light and the infrared laser runs continuously at 2 mW of power during the measurement. Software 4.45SP2 has no fixation target light, and the i...

The changes in pupil size were recorded by infrared pupillographic methods in response to light flashes of different durations and intensities for a 13 degree 34 minute centrally fixated circular field. For such stimuli, the threshold intensities for (rod) vision and for the pupil response were found to be about the same. The response amplitudes were related to the logarithm of the flash energy...